Interspecific cornus hybrid designated KF 111-1

ABSTRACT

An advanced generation interspecific hybrid of  Cornus kousa  and  C. florida  that is distinguished by its exceptionally high vigor, attractive foliage, very floriferous display of white floral bracts, high level of winter hardiness, tolerance of drought and shade, and high resistance to the incitants of Powdery Mildew and Dogwood Anthracnose.

BACKGROUND OF THE INVENTION

This new cultivar is a product of a longstanding detailed program of interspecific hybridization and selection of dogwoods, in this instance a cross of an F₁ interspecific hybrid of Cornus kousa×C. florida ‘Sweetwater’ backcrossed to an unrelated C. kousa. The progeny were carefully retained and characteristics analyzed for their differences and outstanding value as potential commercial varieties or cultivars.

The particular seedling hereof were selected from certain progeny grown in a cultivated area and, as a result, have in turn been asexually reproduced by grafting, usually by T-budding or chip-budding. It can also be propagated by softwood stem cuttings. The reproduction and actual growth and selection of the new cultivar took place in the vicinity of New Brunswick, N.J. and has been found to be distinctive as to its winter-hardiness in that area, USDA Plant Hardiness Map Zone 6a.

As will be understood from the detailed description of the invention that appears hereinafter, the new cultivar is in fact outstanding and readily identified as such. With the foregoing in mind, the description that follows will be understood as clearly defining the new cultivar, the desirable characteristics of which are the result of such a program as has been heretofore suggested.

SUMMARY OF THE INVENTION

The variety was originated or discovered in a cultivated area on a horticulture farm near New Brunswick, N.J. from a cross in June, 1989 between an F₁ interspecific hybrid (seed parent) resulting from a controlled cross of Cornus kousa×C. florida ‘Sweetwater’, and an unnamed C. kousa (pollen parent). The complete parentage of the claimed plant can be summed as follows:

-   -   (Cornus kousa×C. florida ‘Sweetwater’)×C. kousa         None of the antecedent parent plants are patented.

The seedling which became this new cultivar emerged in a seed flat on Mar. 8, 1991 and, subsequently, was transplanted to progressively larger plant-growing containers as follows: one gallon, Mar. 21, 1991; two-gallon, May 22, 1991; 3-gallon, Jul. 25, 1991; 4.5 gallon, Jun. 16, 1992; 7 gallon, Apr. 13, 1993; 15 gallon, Aug. 6, 1993. On Oct. 10, 1994, the plant was field planted at a research site in Millstone, N.J. where it has been thoroughly tested to the present time. It has also been propagated in Tennessee and Oregon. To the best of our knowledge, this new variety is the first reported advanced generation interspecific hybrid of these two species. Furthermore, its fruit has ornamental value as contrasted with other hybrids of these species. The fall foliage of the plant is quite spectacular.

BRIEF DESCRIPTION OF THE DRAWINGS

This new variety of dogwood is illustrated by the accompanying photographic drawings, depicting the plant by the best possible color representation using color photography. All color references below are measured against The Royal Horticultural Society Colour Chart (R.H.S.). Colors of foliage, floral bracts, and other plant parts may vary from year to year depending on horticultural practices, light conditions, air temperature, soil fertility, etc.

FIG. 1 shows the original seedling tree of the present invention after 17 years;

FIG. 2 shows leaf and floral display of original seedling at the peak of floral display;

FIG. 3 shows a single flower head in bloom;

FIG. 4 shows two fruits which illustrate the difference between a fruit containing no drupelets with a viable developing seed, and a fruit showing the enlarged fleshy area around a drupelet containing a seed; and

FIG. 5 shows the foliage and fruit (most contain no viable seed) on several branches.

BOTANICAL DESCRIPTION OF THE INVENTION

Botanical designation:

-   -   (Cornus kousa×C. florida ‘Sweetwater’)×C kousa.

VARIETY DENOMINATION

KF 111-1

-   Plant:     -   -   Form.—Tree.         -   Growth habit.—Tree branched low to ground with upright             branches which spread outward after about 10-15 years.             Height. — 7.62 meters at 20 years. Width. — 6.71 meters at             20 years. The ornamental value of the fruit display of KF             111-1 is a characteristic that distinguished it from all of             the current F1 interspecific hybrids (our Stellar® series             plants) of C. kousa×C. florida since plants of those hybrids             are completely sterile and the fruit they produce are of no             ornamental value.         -   Plant vigor.—Plants of this new variety are very vigorous.             The original seedling was 2.29 meters in height and well             branched at the end of the first growing season. Budded             liners propagated and grown in Tennessee typically reach a             height of 0.91 to 1.22 meters in one year, with a few             reaching a height of 1.52 meters. One-year liners are stout             and well branched. The plants are much more vigorous than             any cultivars of C. florida or C. kousa known to the             inventors and are more vigorous than plants of any of the             seven cultivars of the Stellar® series of hybrid dogwood (F₁             generation interspecific hybrids of C. kousa×C. florida).         -   Cold hardiness.—Original seedling has suffered no winter             injury during the 17 years it has been observed in the field             at Millstone, N.J. in USDA Plant Hardiness Map Zone 6a             (−5° F. to −10° F.).         -   Resistance to insects and disease.—No insect or disease             problems were observed during the 17 years the original             seedling of the cultivar ‘KF 111-1’ has been tested in the             field.         -   Trunk.—Circumference of the crown of the original seedling             at the soil level was 0.95 meters after 20 growing seasons.             Moderate to heavy exfoliating bark on basal 1.52 m of trunk.         -   Color.—197D Greyed-Green Group in areas between lenticels             and 197A to 197B Greyed-Green group in areas of numerous             lenticels. Underside of exfoliating bark — 165B             Greyed-Orange Group. Surface under exfoliated bark — 165D             and 165A Greyed-Orange Group.         -   Lenticels.—approximatelyl 16/cm² on basal 1.83 meters of             trunk.         -   Texture.—Sandpaper rough.         -   Branches.—Color — 197B Greyed-Green Group Texture — fairly             smooth with many small bumps (lenticels) Crotch angle —             large, basal branches — 70°-85°; smaller branches — 25°-40°             Internode length — 13.2 cm (n=25); range 8.9-20.3 cm.             Wherein n is the number of observations. -   Foliage:     -   -   Leaf arrangement.—opposite.         -   Leaf size.—lamina

Average Range in Average Range in Year n length (cm) length (cm) width (cm) width (cm) 2005 10 14.25 11.1-15.5 9.38  8.3-10.8 2009 10 12.8 11.6-16.2 7.20 5.9-9.1

-   -   -    Tip — apiculate Shape — ovate Base — attenuate Margin —             mildly crenulate.         -   Texture.—lamina flat and quite smooth on abaxial surface in             spite of a moderate number of small white hairs. Adaxial             surface has a prominent midrib and four, sometimes five,             pairs of moderately prominent pairs of lateral veins. Small,             short hairs cover the entire surface, which is downy due to             many longer white hairs along the edges of the midrib and             the lateral veins.         -   Other features.—prominent dense tufts of long, light brown             hairs at the axils of the lateral veins and the midrib.         -   Quantity.—many, densely foliaged.         -   Mature foliage color.—Adaxial — closest to, but darker than             137A Green Group with a narrow line (144B Yellow-Green             Group) on the midrib from the tip of the petiole to the base             of the uppermost pair of lateral veins. Abaxial — closest to             138D Green Group with a narrow line (145C Yellow-Green             Group) on the midrib.         -   Autumn foliage color.—attractive. Some leaves remain green             (141A Green Group and 143A Green Group) but most of the             leaves are about 50% green with mottled areas of 166A             Greyed-Orange Group, 145A Yellow-Green Group, 14 B             Yellow-Orange Group, 15A Yellow-Orange Group and 187A             Greyed-Purple Group. Petiole — length: average 11 mm (range             6-15) n=20 — width: average 1.7 mm (range 1-2) n=20 — color:             145A Yellow-Green Group — other feature: dense mat of short             hairs (200B Brown Group) at inner base (point of             attachment).         -   Disease resistance.—Asexually propagated plants of his             hybrid variety have been tested in New Brunswick, N.J.;             Millstone, N.J.; Winchester, Tenn.; and Boring, Oreg. with             no evidence of susceptibility to the incitants of Powdery             Mildew or Dogwood Anthracnose.         -   Shade tolerance.—Plants of this new hybrid have proven to             grow well under conditions of 60%-65% shade, in addition to             thriving under complete exposure to full sunlight.

-   Inflorescence:     -   -   Location where observations were made.—Research field in             Millstone, N.J.         -   Type of inflorescence.—flowerhead. Dense, rounded mound.         -   Number of true flowers per flower head.—Number of flowers

Year n Average Range 2005 10 47.3 40-55 2006 23 52.1 46-61

-   -   -   Peduncle.—size and color:

Average Year n length (cm) width (mm) Color 2005 15 7.1 2.1 145A Yellow-Green Group 2006 23 9.5 2.0 ″ 2009 25 7.2 1.9 ″

-   Floral bracts:     -   -   Number.—Four, in two opposing pairs.         -   Size of floral bracts.—

Length of outer Width of outer Involucral spread of bracts (cm) bracts (cm) outer bracts (cm) Year n Average Average n Average 2005 30 5.28 6.11 15 10.75 2006 48 5.88 5.95 24 11.95

Length of inner Width of inner Involucral spread of bracts (cm) bracts (cm) inner bracts (cm) Year n Average Average n Average 2005 30 5.89 5.43 15 11.99 2006 48 6.30 5.09 24 12.80

The size of the floral bracts will vary due to environmental factors such as temperature, sunlight, rainfall and fertilizer practices. However, the outer, or lower, floral bracts are always shorter and wider than the inner, or upper, floral bracts.

-   -   -   Color.—At start of floral display (early to mid-May):             Adaxial surface — closest to 150D Yellow-Green Group and             slightly lighter toward the tip; fine line of 51A Red Group             along the margins and tips of the bracts. Abaxial surface —             closest to 150D Yellow-Green Group with 155D White Group             toward tip and base; trace of 51A Red Group at margins and             tip. One week after the start of the floral period: Adaxial             surface — closest to 4D Yellow-Group with trace of 52B Red             Group along margins and tip. Abaxial surface — closest to             155B White Group with trace of 52B Red Group along margins             and tip.         -   Shape.—broadly rounded.         -   Apex.—abruptly acute.         -   Base.—broadly acuminate.         -   Bract stalk length.—3-4 mm.         -   Bract stalk width.—5-6 mm.         -   Flower description.—Very floriferous. Single flowers             arranged in compact, dense heads subtended by the large             floral bracts. No observed fragrance. Flowers not             persistent.         -   Flowering habit.—Anthesis of the tiny, relatively             inconspicuous true flowers generally commences 4-6 days             following the onset of the ornamental display of the large             floral bracts which generally occurs in central New Jersey             in early to mid-May and continues approximately for 2.5 to 3             weeks or more depending on the prevailing weather             conditions. Floral development is asynchronous within the             inflorescence.         -   Number of true flowers per flower head.—

Year n average range 2003 125 51.6 40-63 2004 10 53.6 50-58 2005 20 48.9 40-55 2006 33 51.3 43-61 2008 27 50.6 42-62 2009 25 48.0 43-57

The average number of true flowers per flower head of this new cultivar is quite uniform from year to year.

-   Reproductive organs:     -   -   Stamens.—Number per flower — 4. Filament Size — 4-5 mm long             and 0.25-0.30 mm wide. Anther size — approximately 1.0 mm             long and 0.56 mm wide. Color — pre-anthesis: closest to 12A             Yellow Group. post-anthesis: closest to 153D Yellow-Green             Group. Pollen color — closest to 20A Yellow-Orange Group.         -   Pistil.—Number — 1. Style length. — approximately 1.5 mm             long and 0.5 mm diameter. Stigma height. — approximately             0.25 mm. Color of style. — 145A Yellow-Green Group. Color of             stigma. — closest to 153C Yellow-Green Group. -   Fruit:     -   -   Flower head with mature fruit.—Fruits are many two-celled,             one seeded drupelets (ovary inferior), fused at the base in             areas surrounding a drupelet containing a developing seed,             and forming a multiple fruit. A low percentage of the             drupelets contain a developing seed, whereas all of the             known F₁ interspecific hybrids of C. kousa×C. florida in             commerce are extremely cross-sterile. However, a multiple             fruit of ‘KF 111-1’ does not develop into a smooth, rounded,             strawberry-like fruit similar to that of C. kousa unless             there are a number of drupelets that contain a developing             seed which stimulates basal fusion and enlargement of             surrounding drupelets. Thus, the external surface of the             fruit is rough, albeit rounded, due to the small protruding             drupelets that do not contain a developing seed. An             aggregate fruit of C. kousa is plump and rounded with a             smooth surface even in the absence of any developing seed.             The multiple fruit of the KF 111-1 hybrid matures in             mid-September in the vicinity of central New Jersey.         -   Size of fruit.—Height in cms: 2.7 cm (n=43); width in cms:             3.1 cm (n=43).         -   Color.—large fused ovaries near a seed — 46A and 46B Red             Group. smaller, protruding ovaries without a seed: 45A Red             Group.         -   Seed.—round and narrowly tapered to four sections at             proximal end.         -   Color.—161C-161D Greyed-Yellow Group. Size: average length —             7.24 mm (n=15). Average width — 4.62 mm (n=15).         -   Texture.—rough. 

1. A new and distinct cultivar of dogwood tree, substantially as herein shown and described, comprising an advanced generation interspecific hybrid of Cornus kousa×C. florida ‘Sweetwater’ with an unrelated plant of C. kousa. 